About Melphalan Nitrogen mustard alkylating agent, Antineoplastic. Mechanism of Action of Melphalan This nitrogen mustard group alkylating agent forms unstable ethylenimmonium ions, which alkylate or binds with intracellular molecular structures including nucleic acids. Its cytotoxic activity is primarily due to cross linking of strands of DNA & RNA, as well as inhibition of protein synthesis. Interactions for Melphalan Cyclosporine: Potential risk of severe renal failure. Carmustine: The carmustine lung toxicity threshold may be reduced. Cisplatin: Induces renal dysfunction resulting in altered melphalan clearance. Nalidixic Acid: May cause severe haemorrhagic necrotic enterocolitis in children.